1. Field of the Invention
The invention relates to a cage of a rolling bearing, and relates also to a method of assembling a cage of a rolling bearing.
2. Description of the Related Art
As a conventional cage of a rolling bearing, there is a cage of a ball bearing described in Japanese Patent Application Publication No. 2008-64221 (JP 2008-64221 A).
The cage includes a first annular member made of resin, a second annular member made of resin, and a plurality of rivets made of metal. The first annular member has a plurality of cuts each having a semi-circular section. Each cut extends through the first annular member in its radial direction, and opens toward only one side in its axial direction. The cuts are located at intervals in the circumferential direction of the first annular member. The second annular member is identical to the first annular member.
The first annular member and the second annular member are placed on each other such that the cuts of the first annular member, each having a semi-circular section, and the cuts of the second annular member, each having a semi-circular section, constitute holes each having a circular section. The holes each having a circular section constitute pockets that accommodate balls. Portions of the first and second annular members, which are located between the pockets adjacent to each other in the circumferential direction, constitute cage bars.
The first and the second annular members have rivet insertion holes at portions corresponding to the cage bars. When the first and second annular members are placed on each other to constitute the pockets, the rivet insertion holes of the first annular member and the rivet insertion holes of the second annular member are communicated with each other.
The rivets are passed through the rivet insertion holes of the first annular member and the rivet insertion holes of the second annular member. The rivets couple the first annular member and the second annular member to each other. Specifically, the end portions of the rivets are swaged. One end portion of each rivet is engaged with a portion of the first annular member, which is on the opposite side of the first annular member from the second annular member in the axial direction. Further, the other end portion of each rivet is engaged with a portion of the second annular member, which is on the opposite side of the second annular member from the first annular member in the axial direction.
The conventional cage includes the first and second annular members made of resin, and the rivets made of metal of which the linear expansion coefficient is higher than that of resin. As a result, under a high-temperature environment, the rivets expand more than the first and second annular members. This may cause a possibility that forces with which the rivets press inner peripheral faces that define the rivet insertion holes of the first and second annular members will be excessively large, and stresses generated in the first and second annular members will be excessively high.
On the other hand, under a low-temperature environment, the rivets contract more than the first and second annular members. This may cause a possibility that forces with which the rivets press the first and second annular members will fall below a desired magnitude of force.